Did we... did we actually defend the OP when they said that a ENBY main character would turn their story into a comedy?
......
K.
Back to the point: It's actually a fact that if you have a male MC then you're more likely to get a larger readership. But I think you should look back at what makes a good character a good character and a good story a good story.
As someone who also writes in the action genre (in multiple genders' POVs) I can say that those tropes you listed (harems and/or gl for the "manly" female lead) are played out. If you're not going to do something new with them, they'll be about as successful as the millions of other online versions of them: i.e. not successful at all. You can also consider having more than one MC since I don't think you could respectfully represent a NB main character anyhow.